1. Field of the Invention
The present invention relates to processes for the preparation of compounds endowed with phosphodiesterase (PDE4) inhibitory activity. The present invention also relates to processes for the isolation by crystallization of such a compound and to its use for the preparation of pharmaceutical compositions for inhalation in combination with suitable carriers or vehicles. The present invention also relates to solvates and crystal forms of such a compound. The synthesized product is suitable for use in pharmaceutical applications for instance in the treatment of respiratory diseases.
2. Discussion of the Background
Compounds of formula (I) wherein n is 0 or 1:
with chemical names (S)-3-Cyclopropylmethoxy-4-methanesulfonylamino-benzoic acid 1-(3-cyclopropylmethoxy-4-difluoromethoxy-phenyl)-2-(3,5-dichloro-1-oxy-pyridin-4-yl)-ethyl ester and (S)-3-Cyclopropylmethoxy-4-methanesulfonylamino-benzoic acid 1-(3-cyclopropylmethoxy-4-difluoromethoxy-phenyl)-2-(3,5-dichloro-pyridin-4-yl)-ethyl ester, obtained according to the invention, may be used for prophylactic purposes or for symptomatic relief for a wide range of conditions including respiratory disorders such as chronic bronchitis, chronic obstructive pulmonary disease (COPD), asthma of all types and allergic disease states such as atopic dermatitis and allergic rhinitis. Said compounds are disclosed in WO 2010/089107, which is incorporated herein by reference in it is entirety, as potent PDE4 inhibitors having excellent LPDE4 selectivity.
Processes for the preparation of compounds of formula (I) wherein n is 0 or 1 and analogues thereof, were also disclosed in WO 2010/089107, which is incorporated herein by reference in it is entirety.
Thus, there remains a need for improved processes for the preparation of such compounds.